Metal base plate material for heat exchange plate

ABSTRACT

A metal base plate material includes trip-shaped first regions each having a plurality of first ridges arranged substantially parallel to each other and at substantially equal intervals such that an angle of intersection with a longitudinal direction is greater than or equal to 10° and less than or equal to 25°. Strip-shaped second regions each have a plurality of second ridges arranged substantially parallel to each other and at substantially equal intervals and angled to face the plurality of the first ridges in a crosswise direction. The first regions and second regions are separated by a gap regions therebetween, at substantially equal intervals. First ends on a downstream side of the plurality of the first ridges and second ends on a downstream side of the plurality of the second ridges are positioned differently from each other in the longitudinal directions.

TECHNICAL FIELD

The present invention relates to a metal base plate material for a heatexchange plate.

BACKGROUND ART

Plate-type heat exchangers utilizing condensation heat transfer ofworking media are known. Heat exchange plates to be built into theplate-type heat exchangers are usually formed into complex shapes suchas a herringbone shape and the like to improve heat exchange efficiencyand/or mechanical durability. In general, such heat exchange plates aremanufactured by press forming metal base plate materials.

To further improve the heat exchange efficiency of a heat exchangeplate, a method in which a plurality of minute ridges is provided on asurface of a metal base plate material before press forming has beenproposed (Patent Document 1). In Patent Document 1, two kinds of ridgesare symmetrically formed on a surface of a metal flat plate materialbefore press forming in such a way as to be angled in a V-shape, and agap is provided between these two kinds of ridges. This enablesagitation of a vapor of a working medium, thereby acceleratingcondensation of the working medium, and enables a condensate of theworking medium to be efficiently discharged.

Since the two kinds of ridges provided on the surface of the base platematerial in Patent Document 1 form the symmetrical V-shape with the gapbetween the two kinds of ridges, the condensate flowing down on thesurface of the base plate material is guided by the two kinds of ridgesto be concentrated on a space between the ridges, and the flow slowsdown when passing the gap between ends on the downstream side of theridges. Hence, a new approach needs to be devised to properly dispersethe condensate on the plate material surface and discharge thecondensate more efficiently.

PRIOR ART DOCUMENTS Patent Documents

Patent Document 1: Japanese Unexamined Patent Application, PublicationNo. 2015-161449

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

The present invention has been made in view of the above-describedcircumstances, and an object of the present invention is to provide ametal base plate material for a heat exchange plate which can properlydisperse a condensate of a working medium and efficiently discharge thecondensate.

Means for Solving the Problems

An aspect of the invention made to solve the above problems is a metalbase plate material for a heat exchange plate to be built into aplate-type heat exchanger, wherein at least one surface is provided witha plurality of strip-shaped first regions and a plurality ofstrip-shaped second regions, which are provided alternately and inparallel; the strip-shaped first regions each have a plurality of firstridges arranged substantially parallel to each other and atsubstantially equal intervals such that an angle of intersection with alongitudinal direction is greater than or equal to 10° and less than orequal to 25°; the strip-shaped second regions each have a plurality ofsecond ridges arranged substantially parallel to each other and atsubstantially equal intervals and angled to face the plurality of thefirst ridges in a crosswise direction; the first regions are separatedfrom the second regions adjacent thereto by gap regions therebetween,respectively, at substantially equal intervals; and when one orientationof longitudinal directions of the first regions and the second regionsis defined as a downstream direction, first ends on a downstream side ofthe plurality of the first ridges and second ends on a downstream sideof the plurality of the second ridges are positioned differently fromeach other in the longitudinal directions.

Since the metal base plate material has the gap regions between thefirst regions and the second regions and ends (the first ends and thesecond ends) of two kinds of ridges (the first ridges and the secondridges) are arranged to be positioned differently from each other in thelongitudinal directions of the first regions and the second regions,concentration of a condensate on a space between the ends of the twokinds of ridges can be reduced and the condensate can be properlydispersed. Furthermore, since the two kinds of ridges of the metal baseplate material, which are inclined in opposite directions from eachother with respect to the longitudinal directions, are arranged suchthat the angles of intersection with the longitudinal directions of thefirst regions and the second regions are greater than or equal to 10°and less than or equal to 25°, slowdown of a downward flow of thecondensate can be curbed, enabling efficient discharge of thecondensate.

It is preferred that an average distance between the plurality of thefirst ridges is greater than or equal to 0.1 mm and less than or equalto 1.0 mm, an average distance between the plurality of the secondridges is greater than or equal to 0.1 mm and less than or equal to 1.0mm, and an average distance between the first regions and the secondregions is greater than or equal to 0.2 mm and less than or equal to 4.0mm. In the metal base plate material, since the average distance betweenthe first ridges, the average distance between the second ridges, andthe average distance between the first regions and the second regionsare properly adjusted in this manner, the condensate can be efficientlydischarged.

An amount of positional difference longitudinally between the first endsand the second ends is preferably greater than or equal to 0.1 mm andless than or equal to 5.8 mm. In the metal base plate material, sincethe amount of positional difference longitudinally between the firstends and the second ends is properly adjusted in this manner, thecondensate can be properly dispersed.

An angle of intersection of the second ridges with the longitudinaldirection of the second regions is preferably equal to an absolute valueof the angle of intersection of the first ridges. This is becauseamounts of downward flow of the condensate in the first regions and thesecond regions are effectively balanced.

Effects of the Invention

The metal base plate material for a heat exchange plate of the presentinvention can properly disperse a condensate of a working medium andefficiently discharge the condensate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view showing a part of a surface of a metalbase plate material of an embodiment of the present invention.

FIG. 2 is a schematic perspective cross-sectional view showing a part ofa cross-section taken along an A-A line around the surface of the metalbase plate material in FIG. 1.

DESCRIPTION OF EMBODIMENTS

Embodiments of the metal base plate material for a heat exchange plateaccording to the present invention will be described in detail belowwith reference to the drawings.

Metal Base Plate Material

A metal base plate material 1 in FIG. 1 is a metal base plate materialfor a heat exchange plate to be built into a plate-type heat exchanger.A material for the metal base plate material 1 is not particularlylimited, but for example, titanium is used. The metal base platematerial 1 is a flat plate material serving as a material formanufacturing a heat exchange plate, and when it is to be built into aplate-type heat exchanger, it is formed into the heat exchange plate bypress forming. As the metal base plate material 1, a rectangular platewith long sides of 1,200 mm, short sides of 800 mm, and an averagethickness of greater than or equal to 0.5 mm and less than or equal to1.0 mm is used, although there is no particular limitation.

A plurality of strip-shaped first regions 2 and a plurality ofstrip-shaped second regions 3 are provided alternately and in parallelon a surface of the metal base plate material 1. It is to be noted thatthe surface having the first regions 2 and the second regions 3 is atleast one surface of the metal base plate material 1, and may be oneside of the metal base plate material 1 or both sides of the metal baseplate material 1.

First Regions

The first regions 2 are strip-shaped regions provided on the surface ofthe metal base plate material 1. The plurality of the first regions 2 isprovided such that the first regions 2 are substantially parallel toeach other. Each of the first regions 2 has a plurality of first ridges21 arranged substantially parallel to each other and at substantiallyequal intervals such that the angle of intersection with a longitudinaldirection is θ₁.

The lower limit of an average width Z₁ in a crosswise direction of thefirst regions 2 is preferably 1 mm, more preferably 2 mm, and still morepreferably 3 mm. Meanwhile, the upper limit of the average width Z₁ ispreferably 20 mm, more preferably 18 mm, and still more preferably 16mm. If the average width Z₁ is less than the lower limit, agitation of avapor of a working medium may be insufficient, resulting in failure toaccelerate condensation of the working medium. Conversely, if theaverage width Z₁ is greater than the upper limit, a condensate may beretained in the first regions 2, resulting in inefficient discharge ofthe condensate. It is to be noted that “average width” refers to anaverage value of widths at five arbitrarily selected points in oneobject.

(First Ridges)

In the first regions 2, the plurality of the first ridges 21 is providedsuch that the first ridges 21 are substantially parallel to each otherand at substantially equal intervals. The first ridges 21 are long,thin, rod-shaped ridges in plan view, and each has such a length thatboth ends reach both side portions of the first region 2, which isstrip-shaped. It is to be noted that, although the first ridges 21 inFIG. 1 are substantially rectangular, the first ridges 21 only need tobe formed so that two long sides are substantially parallel to eachother in plan view; both ends may be curved, for example. Further, amethod for forming ridges on the surface of the metal base platematerial 1 is not particularly limited, but for example, a method inwhich protrusions/recessions are transferred during rolling, and thelike are employed.

The angle of intersection θ₁ of the first ridges 21 with thelongitudinal direction of the first regions 2 is set to an acute angleto curb slowdown of a downward flow of the condensate. The lower limitof the angle of intersection θ₁ is preferably 10°, more preferably 12°,and still more preferably 13°. Meanwhile, the upper limit of the angleof intersection θ₁ is preferably 25°, more preferably 22°, and stillmore preferably 20°. If the angle of intersection θ₁ is less than thelower limit, the condensate may fail to be properly guided along sidesof the first ridges 21. Conversely, if the angle of intersection θ₁ isgreater than the upper limit, the condensate may be retained in thefirst regions 2 and inefficiently discharged. It is to be noted that“angle of intersection” refers to an acute angle of two angles formedwhen two straight lines cross each other.

The lower limit of an average width a₁ in a crosswise direction of thefirst ridges 21 is preferably 0.10 mm, more preferably 0.11 mm, andstill more preferably 0.12 mm. Meanwhile, the upper limit of the averagewidth a₁ is preferably 1.0 mm, more preferably 0.8 mm, and still morepreferably 0.6 mm. If the average width a₁ is less than the lower limit,strength of the first ridges 21 may be insufficient. Conversely, if theaverage width a₁ is greater than the upper limit, the condensate mayflow down on top surfaces of the first ridges 21, resulting in failureto properly guide the condensate along the sides of the first ridges 21.

The lower limit of an average distance b₁ between two of the firstridges 21 is preferably 0.1 mm, more preferably 0.2 mm, and still morepreferably 0.3 mm. Meanwhile, the upper limit of the average distance b₁is preferably 1.0 mm, more preferably 0.9 mm, and still more preferably0.8 mm. If the average distance b₁ is less than the lower limit, thecondensate may spill over the top surfaces of the first ridges 21,resulting in failure to properly guide the condensate along the sides ofthe first ridges 21. Conversely, if the average distance b₁ is greaterthan the upper limit, the condensate may be retained between the firstridges 21 and inefficiently discharged. It is to be noted that “averagedistance” is an average of distances in the crosswise direction of theridges, and refers to an average value of five arbitrarily selected fivebetween two ridges.

The lower limit of an average height h of the first ridges 21 withrespect to the surface of the metal base plate material 1 is preferably0.02 mm, more preferably 0.03 mm, and still more preferably 0.04 mm.Meanwhile, the upper limit of the average height h is preferably 0.10mm, more preferably 0.09 mm, and still more preferably 0.08 mm. If theaverage height h is less than the lower limit, agitation of the vapor ofthe working medium may be insufficient, resulting in failure toaccelerate condensation of the working medium. Conversely, if theaverage height h is greater than the upper limit, processing cost mayincrease.

Second Regions

Like the first regions 2, the second regions 3 are strip-shaped regionsprovided on the surface of the metal base plate material 1. Theplurality of the second regions 3 is provided such that the secondregions 3 are substantially parallel to each other. Each of the secondregions 3 has a plurality of second ridges 31 arranged substantiallyparallel to each other and at substantially equal intervals, and at anangle θ₂ to face the plurality of the first ridges 21 in a crosswisedirection.

The lower limit of an average width Z₂ in the crosswise direction of thesecond regions 3 is preferably 1 mm, more preferably 2 mm, and stillmore preferably 3 mm. Meanwhile, the upper limit of the average width Z₂is preferably 20 mm, more preferably 18 mm, and still more preferably 16mm. If the average width Z₂ is less than the lower limit, agitation ofthe vapor of the working medium may be insufficient, resulting infailure to accelerate condensation of the working medium. Conversely, ifthe average width Z₂ is greater than the upper limit, the condensate maybe retained in the second regions 3, resulting in inefficient dischargeof the condensate.

(Second Ridges)

In the second regions 3, the plurality of the second ridges 31 isprovided such that the second ridges 31 are substantially parallel toeach other and at substantially equal intervals. Similarly to the firstridges 21, the second ridges 31 are long, thin, rod-shaped ridges inplan view, and each has such a length that both ends reach both sideportions of the second region 3, which is strip-shaped. Although in FIG.1, a shape of the second ridges 31 is a substantially rectangular shapesimilar to that of the first ridges 21, the second ridges 31 only needto be formed so that two long sides are substantially parallel to eachother in plan view, similarly to the first ridges 21. In addition, inlight of a balance of amounts of downward flow of the condensate, it ispreferable that the shape of the second ridges 31 are similar to thefirst ridges 21 in plan view and that a height of the second ridges 31with respect to the surface of the metal base plate material 1 is equalto the height h of the first ridges 21 with respect to the surface ofthe metal base plate material 1 as shown in FIG. 2.

The second ridges 31 are angled to face the first ridges 21 in thecrosswise direction; therefore, when one orientation of the longitudinaldirections of the first regions 2 and the second regions 3 is defined asa downstream direction, first ends 21 a on a downstream side of theplurality of the first ridges 21 and second ends 31 a on a downstreamside of the plurality of the second ridges 31 are adjacent to each otherwith gap regions 4 interposed therebetween.

An angle of intersection θ₂ of the second ridges 31 with thelongitudinal direction of the second regions 3 is set to an acute angleto curb the slowdown of the downward flow of the condensate. The lowerlimit of the angle of intersection θ₂ is preferably 10°, more preferably12°, and still more preferably 13°. Meanwhile, the upper limit of theangle of intersection θ₂ is preferably 25°, more preferably 22°, andstill more preferably 20°. If the angle of intersection θ₂ is less thanthe lower limit, the condensate may fail to be properly guided alongsides of the second ridges 31. Conversely, if the angle of intersectionθ₂ is greater than the upper limit, the condensate may be retained inthe second regions 3 and inefficiently discharged. It is to be notedthat in light of the balance of the amounts of downward flow of thecondensate, an absolute value of the angle of intersection θ₁ ispreferably equal to that of the angle of intersection θ₂.

The lower limit of an average width a₂ in the crosswise direction of thesecond ridges 31 is preferably 0.10 mm, more preferably 0.11 mm, andstill more preferably 0.12 mm. Meanwhile, the upper limit of the averagewidth a₂ is preferably 1.0 mm, more preferably 0.8 mm, and still morepreferably 0.6 mm. If the average width a₂ is less than the lower limit,the strength of the second ridges 31 may be insufficient. Conversely, ifthe average width a₂ is greater than the upper limit, the condensate mayflow down on top surfaces of the second ridges 31, resulting in failureto properly guide the condensate along the sides of the second ridges31. It is to be noted that in light of the balance of the amounts ofdownward flow of the condensate, the average width a₁ is preferablyequal to the average width a₂.

The lower limit of an average distance b₂ between two of the secondridges 31 is preferably 0.1 mm, more preferably 0.2 mm, and still morepreferably 0.3 mm. Meanwhile, the upper limit of the average distance b₂is preferably 1.0 mm, more preferably 0.9 mm, and still more preferably0.8 mm. If the average distance b₂ is less than the lower limit, thecondensate may spill over the top surfaces of the second ridges 31,resulting in failure to properly guide the condensate along the sides ofthe second ridges 31. Conversely, if the average distance b₂ is greaterthan the upper limit, the condensate may be retained between the secondridges 31 and inefficiently discharged. It is to be noted that in lightof the balance of the amounts of downward flow of the condensate, theaverage distance b₁ is preferably equal to the average distance b₂.

When one orientation of the longitudinal directions of the first regions2 and the second regions 3 is defined as the downstream direction, thefirst ends 21 a on the downstream side of the plurality of the firstridges 21 and the second ends 31 a on the downstream side of theplurality of the second ridges 31 are positioned differently from eachother in the longitudinal directions as shown in FIG. 1. An amount ofpositional difference longitudinally between the first ends 21 a and thesecond ends 31 a includes an amount of positional difference W₁ in acase where the first end 21 a is on the downstream side with respect tothe second end 31 a and an amount of positional difference W₂ in a casewhere the first end 21 a is on the upstream side with respect to thesecond end 31 a. In light of the balance of the amounts of downward flowof the condensate, the amount of positional difference W₁ is preferablyequal to the amount of positional difference W₂; however, there is noparticular limitation, and the amount of positional difference W₁ may bedifferent from the amount of positional difference W₂. It is to be notedthat “an end on the downstream side of ridges” refers to a downstreamterminal on an upstream long side of the ridge.

The lower limit of the amount of positional difference W₁ longitudinallybetween the first end 21 a and the second end 31 a is preferably 0.1 mm,more preferably 0.6 mm, and still more preferably 1.0 mm. Meanwhile, theupper limit of the amount of positional difference W1 is preferably 5.8mm, more preferably 4.5 mm, and still more preferably 3.5 mm. If theamount of positional difference W₁ is less than the lower limit,concentration of the condensate on spaces between the first ends 21 aand the second ends 31 a may fail to be reduced and the condensate maybe improperly dispersed. Conversely, if the amount of positionaldifference W₁ exceeds the upper limit, the condensate may fail to beproperly guided along the first ridges 21 and the second ridges 31. Itis to be noted that the upper limit and the lower limit of the amount ofpositional difference W₂ is similar to that of W₁.

Gap Regions

The first regions 2 are separated from the second regions 3 adjacentthereto by the gap regions 4 therebetween, respectively, atsubstantially equal intervals. The gap regions 4 are strip-shapedregions parallel to the longitudinal directions of the first regions 2and the second regions 3, and the first regions 2 and the second regions3 are arranged parallel to each other with the gap regions 4 interposedtherebetween. Protrusions/recessions such as ridges and the like are notformed in the gap regions 4, and most of the condensate flows down thegap regions 4 in a zigzag manner.

The lower limit of an average distance X between the first regions 2 andthe second regions 3 is preferably 0.2 mm, more preferably 0.3 mm, andstill more preferably 0.4 mm. Meanwhile, the upper limit of the averagedistance X is preferably 4.0 mm, more preferably 3.5 mm, and still morepreferably 3.0 mm. If the average distance X is less than the lowerlimit, the condensate may be inefficiently discharged. Conversely, ifthe average distance X is greater than the upper limit, the condensatemay fail to be properly guided along the first ridges 21 and the secondridges 31.

(Advantages)

Since the metal base plate material 1 has the gap regions 4 between thefirst regions 2 and the second regions 3 and ends (the first ends 21 aand the second ends 31 a) of two kinds of ridges (the first ridges 21and the second ridges 31) are arranged to be positioned differently fromeach other in the longitudinal directions of the first regions 2 and thesecond regions 3, the concentration of the condensate on the spacesbetween the ends of the two kinds of ridges can be reduced, and thecondensate can be properly dispersed. Moreover, in the metal base platematerial 1, since the two kinds of ridges are arranged such that theangles of intersection with the longitudinal directions of the firstregions 2 and the second regions 3 is greater than or equal to 10° andless than or equal to 25°, the slowdown of the downward flow of thecondensate can be curbed, enabling efficient discharge of thecondensate.

Furthermore, in the metal base plate material 1, the average distance b₁between the first ridges 21, the average distance b₂ between the secondridges 31, and the average distance X between the first regions 2 andthe second regions 3 are properly adjusted, enabling efficient dischargeof the condensate.

Furthermore, in the metal base plate material 1, the amount ofpositional difference W₁ and W₂ longitudinally between the first ends 21a and the second ends 31 a is properly adjusted, enabling the condensateto be properly dispersed.

OTHER EMBODIMENTS

The metal base plate material for a heat exchange plate of the presentinvention is not limited to the above embodiment.

In the above embodiment, the metal base plate material 1 having the gapregions 4 between the first regions 2 and the second regions 3 has beendescribed. However, it is only necessary that the gap regions 4 areprovided between the first ends 21 a and the second ends 31 a; it is notnecessary that the gap regions 4 be provided between ends on theupstream side of the first ridges 21 and ends on the upstream side ofthe second ridges 31.

EXAMPLES

Hereinafter, the present invention will be described in detail by way ofExamples; however, the Examples are not construed as limiting thepresent invention.

As a test of condensation heat transfer performance, overall heattransfer coefficients were evaluated by using metal base plate materialsNo. 1 to No. 4. Hydrofluorocarbon (R134a) was used as a working mediumto be in contact with surfaces of the metal base plate materials, andcold water was used as a refrigerant to be in contact with rear surfacesof the metal base plate materials to condense the working medium. Theworking medium, whose inflow temperature was set to 30° C. with aheater, was made to flow onto the surfaces of the metal base platematerials at a pressure of 0.68 MPa. Cold water was brought to an inflowtemperature of 20° C. and made to flow onto the rear surfaces of themetal base plate materials at a flow rate of 3 L/min. Further, a heattransfer area of the metal base plate materials was 17,500 mm², and adepth W was 2 mm. The overall heat transfer coefficients were calculatedusing the temperature at which the cold water flowed onto the rearsurfaces of the metal base plate materials, the temperature at which thecold water flowed out from the rear surfaces of the metal base platematerials, the heat transfer area of the metal base plate materials, andthe difference between the inflow temperature of the working medium andthe inflow temperature of the cold water.

The surfaces of the metal base plate materials, which were to be incontact with the working medium, are as follows. It is to be noted thatthe metal base plate materials No. 1 and No. 2 are the metal base platematerial 1 of the above embodiment, and the metal base plate materialNo. 3 is the metal base plate material 1 of the above embodiment whereinthe angle of intersection θ of the ridges with the longitudinaldirections of regions in which the ridges are provided, and the amountof positional difference W longitudinally between the ends of the ridgesare outside ranges of the embodiment. Further, the metal base platematerial No. 4 is a flat plate material wherein a surface has no ridge.It is to be noted that the first ridges and the second ridges of themetal base plate materials No. 1 to No. 3 are identical in shape.

Metal Base Plate Material No. 1

Height h of the ridges: 0.05 mm; width a in the crosswise directions ofthe ridges: 0.125 mm; distance b between the ridges: 0.6 mm; angle ofintersection θ of the ridges with the longitudinal directions of theregions in which the ridges are provided: 15°; distance X between theregions in which the ridges are provided: 0.98 mm; width Z in thecrosswise directions of the regions in which the ridges are provided:4.88 mm; amount of positional difference W longitudinally between theends of the ridges: 1.4 mm

Metal Base Plate Material No. 2

Height h of the ridges: 0.05 mm; width a in the crosswise directions ofthe ridges: 0.125 mm; distance b between the ridges: 0.6 mm; angle ofintersection θ of the ridges with the longitudinal directions of theregions in which the ridges are provided: 15°; distance X between theregions in which the ridges are provided: 0.49 mm; width Z in thecrosswise directions of the regions in which the ridges are provided:2.44 mm; amount of positional difference W longitudinally between theends of the ridges: 1.4 mm

Metal Base Plate Material No. 3

Height h of the ridges: 0.05 mm; width a in the crosswise directions ofthe ridges: 0.125 mm; distance b between the ridges: 0.6 mm; angle ofintersection θ of the ridges with the longitudinal directions of theregions in which the ridges are provided: 45°; distance X between theregions in which the ridges are provided: 4 mm; width Z in the crosswisedirections of the regions in which the ridges are provided: 20 mm;amount of positional difference W longitudinally between the ends of theridges: 0 mm

The test results are as follows: the overall heat transfer coefficientof the metal base plate material No. 1 was 3,592 W/m²K, the overall heattransfer coefficient of the metal base plate material No. 2 was 3,436W/m²K, the overall heat transfer coefficient of the metal base platematerial No. 3 was 2,518 W/m²K, and the overall heat transfercoefficient of the metal base plate material No. 4 was 2,305 W/m²K,confirming that the metal base plate materials No. 1 and No. 2 showedhigh overall heat transfer coefficients. Thus, it can be concluded thatthe overall heat transfer coefficient of a metal base plate material isimproved by properly arranging ridges on a surface of the metal baseplate material as in the metal base plate materials No. 1 and No. 2.

The metal base plate material for a heat exchange plate of the presentinvention can properly disperse a condensate of a working medium andefficiently discharge the condensate.

EXPLANATION OF THE REFERENCE SYMBOLS

-   1 Metal base plate material-   2 First region-   3 Second region-   4 Gap region-   21 First ridge-   21 a First end-   31 Second ridge-   31 a Second end

1. A metal base plate material for a heat exchange plate to be builtinto a plate-type heat exchanger, wherein at least one surface isprovided with a plurality of strip-shaped first regions and a pluralityof strip-shaped second regions, which are provided alternately and inparallel, the strip-shaped first regions each comprise a plurality offirst ridges arranged substantially parallel to each other and atsubstantially equal intervals such that an angle of intersection with alongitudinal direction is greater than or equal to 10° and less than orequal to 25°, the strip-shaped second regions each comprise a pluralityof second ridges arranged substantially parallel to each other and atsubstantially equal intervals and angled to face the plurality of thefirst ridges in a crosswise direction, the first regions are separatedfrom the second regions adjacent thereto by gap regions therebetween,respectively, at substantially equal intervals, and when one orientationof longitudinal directions of the first regions and the second regionsis defined as a downstream direction, first ends on a downstream side ofthe plurality of the first ridges and second ends on a downstream sideof the plurality of the second ridges are positioned differently fromeach other in the longitudinal directions.
 2. The metal base platematerial according to claim 1, wherein an average distance between theplurality of the first ridges is greater than or equal to 0.1 mm andless than or equal to 1.0 mm, an average distance between the pluralityof the second ridges is greater than or equal to 0.1 mm and less than orequal to 1.0 mm, and an average distance between the first regions andthe second regions is greater than or equal to 0.2 mm and less than orequal to 4.0 mm.
 3. The metal base plate material according to claim 1,wherein an amount of positional difference longitudinally between thefirst ends and the second ends is greater than or equal to 0.1 mm andless than or equal to 5.8 mm.
 4. The metal base plate material accordingto claim 1, wherein an angle of intersection of the second ridges withthe longitudinal direction of the second regions is equal to an absolutevalue of the angle of intersection of the first ridges.